TH400 Leaking-Opinions

[11555wally]

My 86 C10 has had several leaks when I got it and I'm gradually taking care of them. The one I'm working on now is the transmission. I recently unhooked the rear springs to change bushings and notice some trans fluid was coming out when the rearend was quite a ways below the transmission. I now have the truck up on blocks and it seems to be leaking a minor amount on the floor and appears to be coming from the vent hole on the yoke. It does not appear to be coming around the seal. After cleaning it up there will be a drop on the u-joint in a couple of hours I've read about this on this forum and wondered what the latest fix for this is. Some say to plug the hole, some say to change the O-ring on the tailshaft, others said they can't find the O-ring. I should say that the truck is up on blocks and hasn't been driven for 6 weeks or more and it is still leaking a little. I do not know the history of this transmission but it seemed to shift OK what little I drove it. Would appreciate your opinions on what to do about the leak.